Member for the formation of at least one electrode and/or one sensor

Abstract

A member has a solid carrier and a thin oxide layer which is arranged thereon and consists of iridium oxide and/or possibly at least one oxide of at least one other metal belonging to the fifth or sixth period and to one of the subgroups 5b, 6b, 7b and 8 of the Periodic Table of chemical elements and/or zirconium oxide. The oxide layer is monocrystalline and therefore very stable. The member can serve, for example, for the formation of at least one electrode which serves as a proton donor and/or proton acceptor and/or for the measurement and/or change of the pH value and/or for a coulometric measurement or for holding biologically active molecules and at the same time as an electrode and/or optical sensor.

What is claimed is: 
     
       1. A member for use during chemical analysis of a substance to which the member is exposed, comprising: a carrier; and a metal oxide layer which is arranged on the carrier and which has a plurality of progressively increasing oxidation states as viewed across a thickness of said oxide layer, and a free surface region defining a highest oxidation state, the metal in the layer being selected from the group consisting of metals belonging to one of the fifth and sixth periods and to one of the subgroups 5b, 6b, 7b, and 8 of the Periodic Table of chemical elements and zirconium, wherein at least that part of the oxide layer which forms the free surface region of said layer is monocrystalline. 
     
     
       2. A member as claimed in claim 1, wherein the carrier comprises, a metallic support on which the oxide layer is arranged. 
     
     
       3. A member, as claimed in claim 2, wherein the carrier further comprises a carrier part which consists of alumina and on which a metal layer forming the stated metallic support is arranged. 
     
     
       4. A member for the formation of at least one electrode having a carrier and an oxide layer which is arranged thereon, said oxide layer having a plurality of progressively increasing oxidation states as viewed across a thickness of said oxide layer, and a free surface region defining a highest oxidation state, said oxide layer consisting of a metal oxide of a metal belonging to a group consisting of Ir, Pd, Ru, Ta and Nb, wherein at least that part of said oxide layer which forms said free surface region is monocrystalline. 
     
     
       5. A member as claimed in claim 4, wherein said carrier comprises a metallic support on which said oxide layer is arranged. 
     
     
       6. A member as claimed in claim 5, wherein said oxide layer consists of an oxide of a single metal, and wherein said metallic support also consists of said single metal. 
     
     
       7. A member as claimed in claim 5, wherein said carrier has a carrier part which consists of alumina and on which a metal layer forming said metallic support is arranged. 
     
     
       8. A member as claimed in claim 7, wherein said carrier part consists of a piece of sapphire. 
     
     
       9. A member as claimed in claim 5, further comprising an electrically insulating covering which consists of a material other than said oxide layer and which covers the edge of said metallic support and of said oxide layer, separating them from a space adjacent to said member. 
     
     
       10. A member as claimed in claim 9, wherein said covering consists of silicon or silica. 
     
     
       11. A member as claimed in claim 4, wherein said oxide layer is light-transmitting in said free surface region. 
     
     
       12. A member as claimed in claim 4, wherein one and the same carrier carries at least one electrode having said oxide layer and also at least one additional electrode whose free surface is formed by a material differing from said oxide layer. 
     
     
       13. A member as claimed in claim 12, wherein said material which differs from said oxide layer and serves for forming said at least one additional electrode consists of one substance belonging to a group consisting of silver chloride, calomel and platinum. 
     
     
       14. A member as claimed in claim 4, wherein said carrier has an electrically insulating carrier part and has at least two of said oxide layers which serve as electrodes and are a distance apart. 
     
     
       15. A member for the formation of at least one electrode, serving for at least one of measuring a pH value of a liquid, of measuring an ion concentration of a liquid, of measuring a buffer capacity of a liquid, of detecting electrical nerve signals and of stimulating electrical nerve signals, having a carrier and an oxide layer which is arranged thereon, said oxide layer having a plurality of progressively increasing oxidation states as viewed across a thickness of said oxide layer, and a free surface region defining a highest oxidation state, said oxide layer consisting of a metal oxide of a metal belonging to a group consisting of Ir, Pd, Ru, Ta and Nb, wherein at least that part of said oxide layer which forms said free surface region is monocrystalline. 
     
     
       16. A member having a carrier and an oxide layer which is arranged thereon, said oxide layer having a plurality of progressively increasing oxidation states as viewed across a thickness of said oxide layer, and a free surface region defining a highest oxidation state, for holding biologically active molecules of at least one of a protein and peptide, said oxide layer consisting of a metal oxide of a metal belonging to a group consisting of Ir, Pd, Ru, Ta and Nb, wherein at least that part of said oxide layer which forms said free surface region is monocrystalline. 
     
     
       17. A means for the coulometric investigation of a liquid, having a member which has a carrier and an oxide layer which is arranged thereon, said oxide layer having a plurality of progressively increasing oxidation states as viewed across a thickness of said oxide layer, said oxide layer further having a free surface region defining a highest oxidation state, said oxide layer consisting of a metal oxide of a metal belonging to a group consisting of Ir, Pd, Ru, Ta and Nb, wherein at least that part of said oxide layer which forms said free surface region is monocrystalline, wherein four electrodes are arranged on said carrier which can be brought into contact with said liquid, one of said electrodes serving as a pH measurement electrode, one as a control electrode for controlling the pH value of said liquid by exchanging protons with said liquid, one as a reference electrode for said pH measurement, one as a counter-electrode to said control electrode, said control electrode being composed of the monocrystalline oxide layer, and wherein an electronic measuring apparatus electrically connected to said four electrodes is present and is designed to determine the pH value of said liquid on the basis of an electric potential difference between said pH measurement electrode and said reference electrode and to generate an electric current flowing between said control electrode and said counter-electrode through said liquid and to regulate said current so that the measured pH value is equal to a setpoint value. 
     
     
       18. A means as claimed in claim 17, wherein said pH measurement electrode likewise comprises a monocrystalline oxide layer, wherein said control electrode approximately encloses said pH measurement electrode and wherein said reference electrode and said counter-electrode are arranged outside said control electrode. 
     
     
       19. A means as claimed in claim 17, wherein said carrier, together with at least one part connected thereto, defines a hollow space closed off from the surroundings and adjacent to said four electrodes. 
     
     
       20. A means as claimed in claim 17, wherein said electronic measuring apparatus is formed in order to determine the quantity of electric charge forming said electric current during measurement.